This roasted vegetable wrap also makes a great portable picnic dish.
1. Position racks in top and bottom thirds of oven, then preheat to 400F.
2. Toss cauliflower and pepper with 2 tbsp oil, garlic, 1/2 tsp cumin, 1/4 tsp salt and 1/8 tsp nutmeg on a rimmed baking sheet. Pat chickpeas dry with a clean kitchen towel, then toss with remaining 1 tbsp oil, 1/2 tsp cumin, 1/4 tsp salt and 1/8 tsp nutmeg on another rimmed baking sheet.
3. Bake cauliflower mixture in top third and chickpeas in bottom third of oven, tossing and switching sheets halfway through cooking, until veggies are tender-crisp and chickpeas are almost crisp, 24 to 28 min. Let cool slightly, then slice peppers.
4. To assemble wraps, divide and spread half of tzatziki over tortillas, leaving a 1/2-in. border. Divide spinach, chickpeas and cauliflower mixture among tortillas, then sprinkle with cilantro. Fold sides of tortilla over filling, then roll tightly, starting with edge nearest you. Cut each wrap in half and serve with remaining tzatziki.